The present invention relates in general to an apparatus for use in aligning medical instruments which are adapted for use during various surgical procedures, and more particularly, to an apparatus for aligning a resection guide for use in arthroplastic surgery of a patient's knee.
Arthroplasty is a known surgical procedure for replacing the knee joint which has been damaged due to disease or trauma. Total knee arthroplasty involves the replacement of portions of the patellar, femur and tibia with an artificial knee prostheses. In particular, a distal portion of the femur and proximal portion of the tibia are cut away, i.e., resected, and replaced with artificial knee components. As use herein, when referring to bones or other body parts, the term “proximal” means closest to the heart and the term “distal” means more distant from the heart.
There are several types of knee prostheses known in the art. One type is commonly referred to as a resurfacing type. In these prostheses, the articular surface of the distal femur and proximal surface of the tibia are resurfaced with respective metal and plastic condylar-type articulate bearing components. The femoral component is often a metallic alloy construction which provides medial and lateral condylar bearing surfaces of multi-radius design of similar shape and geometry as the natural distal femur or femoral-side of the knee joint. The tibial component usually includes a distal metal base component and a proximal interlocking plastic component or insert. The plastic tibial plateau bearing surfaces are of concave multi-radius geometry to more or less match the articular geometry of the mating femoral condyles. These knee prostheses components, which provide adequate rotational and translational freedom, require minimal bone resection to accommodate the components within the boundaries of the available joint space.
The surgical implant of a prosthetic knee joint requires that the distal femur and proximal tibia be prepared to receive the femoral and tibial components by cutting the bone of the femur and tibia to establish accurately located surfaces. Various guides are available to the surgeon for assisting in guiding a medical instrument such as a cutting blade for marking the femoral and tibial cuts which establish the desired resected surfaces. One important feature of these guides is the ability to align the cutting blade accurately when resurfacing the femur and tibia to accommodate the prosthetic knee components. To this end, there is known resection guides suitable for use in total knee arthroplasty from U.S. Pat. Nos. 6,090,114; 5,788,700; and 4,892,093; as well as pending application Ser. No. 09/811,318 entitled Apparatus Used in Performing Femoral and Tibial Resection in Knee Surgery, filed on Mar. 17, 2001, assigned to the same assignee of the present application.
The present invention is specifically directed to an alignment guide intended for any medical condition in which the use of computer-aided surgery may be appropriate, and where a reference to rigid anatomical structures can be identified. More particularly, the present invention is directed to an alignment guide which provides improvements in accurately aligning the cutting blade for resection of bone, for example, the distal femur and proximal tibia during arthroplastic knee surgery.